SCIENCE STATS
Earth’s oceans broke heat records in 2020
The total amount of heat stored in the upper oceans in 2020 was higher
than in any other year on record dating back to the 1950s, researchers
report online January 13 in Advances in Atmospheric Sciences. Climate
scientist Michael Mann of Penn State and colleagues analyzed water tem-
perature data from around the globe. The oceans’ upper 2,000 meters had
234 sextillion, or 10^21 , joules more heat energy in 2020 than the annual
average from 1981 to 2010 (see graph below ). Heat energy storage was up
about 20 sextillion joules from 2019 — suggesting that in 2020, the oceans
absorbed enough heat to boil 1.3 billion kettles of water. The two previous
record holders were 2019 and 2017. “What we’re seeing here is a variant on
the movie Groundhog Day,” Mann says. Overall, based on average land and
sea temperature, 2020 tied with 2016 for Earth’s hottest year on record
(SN Online: 1/14/21). — Maria Temmingc oordinated
electric
attacks that can
send shocked fish
flying from the water. The
researchers haven’t yet measured the
combined voltage of such attacks, but
10 Volta’s electric eels firing together
could, in theory, power something like
100 l ightbulbs, de Santana says. The
stunned, floating prey make easy pick-
ings for the mass of eels. The whole
event lasts about two hours.
So far, such aggregations have beenOnce thought of as lone predators,
Volta’s electric eels (one shown)
have been spotted hunting
in swarms of more than
100 i ndividuals.
observed in
only one lake. But
de Santana suspects
that group hunting may be
advantageous in other lakes and
rivers with large shoals of small fish.
Much of the eels’ range remains under-
explored by scientists, so de Santana
and colleagues are launching a citizen
science project with I ndigenous com-
munities to identify more spots where
many eels live together, de Santana
says. “There is still so much we don’t
know about these organisms.”
— Jonathan Lamberthttp://www.sciencenews.org | February 13, 2021 5NOIRLAB/NSF AND AURA, J. DA SILVAFROM TOP: L. SOUSA; T. TIBBITTSTEASER
A new zinc-air battery
keeps going and going
Zinc-air batteries are lightweight and
compact, but they’re usually not recharge-
able. By tweaking the building materials,
researchers have created a prototype that
could be recharged hundreds of times. Such
long-lasting devices, described in the Jan. 1
Science, could one day power electric cars.
In a standard zinc-air battery, oxygen
from the air enters the cathode and reacts
with water from a liquid called an electro-
lyte to form hydroxide. Hydroxide t ravels
from the cathode to an anode, and then
reacts with zinc to release energy. But this
reaction is not very reversible, making the
battery hard to recharge. The electrolyte
can also degrade the cathode and anode ,
shortening the battery’s life span.
Materials scientist Wei Sun of the
U niversity of Münster in Germany and col-
leagues built a zinc-air battery using a new
electrolyte. Water-repellent ions in the liq-
uid prevent hydroxide from forming at the
cathode surface. Zinc ions from the anode
travel to the cathode and react directly with
oxygen. Running the reaction backward
recharges the battery, and the electrolyte
is not corrosive. In lab tests, Sun’s team
recharged the prototype 320 times over
160 hours. — Maria Temmingstunned in 2012 when his colleague
Douglas Bastos, now a biologist at
the National Institute of Amazonian
Research in Manaus, Brazil, reported
seeing more than 100 eels congregating
and seemingly hunting together in a
small lake in northern Brazil.
Two years later, de Santana’s team
returned to the lake to make more
detailed observations. The nearly
2-meter-long eels lethargically lay in
deeper waters during much of the day,
the researchers found. But at dusk and
dawn, these long dark streaks swirl
together to form a writhing circle more
than 100 strong that herds thousands
of smaller fish into shallower waters.
After corralling the prey, smaller
groups of about 10 eels unleashsend shocked fish
flying from the water. The
researchers haven’t yet measured the
combined voltage of such attacks, but
10 Volta’s electric eels firing togetherOnce thought of as lone predators,
Volta’s electric eels (one shown)
have been spotted hunting
in swarms of more thanobserved in
only one lake. But
de Santana suspects
that group hunting may be
advantageous in other lakes and
rivers with large shoals of small fish.
Much of the eels’ range remains under-
explored by scientists, so de Santana
and colleagues are launching a citizenthe Jan. 20 Astrophysical Journal Letters.
Quasars are thought to grow from
smaller seed black holes that gobble up
matter. Astronomer Feige Wang of the
University of Arizona in Tucson and col-
leagues calculated that even if J0313-1806’s
seed formed right after the universe’s
first stars and grew as fast as possible, it
would have needed a starting mass of at
least 10,000 suns. Seed black holes typi-
cally form through the collapse of massive
stars — a process that can make black holes
with starting masses of only up to a few
thousand suns. A gargantuan seed black
hole may have formed from the collapse of
primordial hydrogen gas, Wang s uggests,
or perhaps J0313-1806’s seed started
small and black holes can grow faster than
s cientists think. — Maria Temming
Change in annual average global ocean heat content, 1958–Year250200150100500−−−150 19592020Ocean heat content anomaly (sextillion joules)The oldest and most distant
quasar known (illustrated)
is prompting astronomers to r e-
examine how black holes grow up.SOURCE: L. CHENG ET AL/ADVANCES IN ATMOSPHERIC SCIENCES 2021notebook.indd 5notebook.indd 5 1/27/21 12:21 PM1/27/21 12:21 PM